There are certain medical procedures that are carried out within a body cavity. One example of such a procedure is tissue ablation. Ablation of the interior lining of a body organ is a procedure which involves heating the organ lining to temperatures which destroy the cells of the lining or coagulate tissue proteins. Such a procedure may be performed as a treatment to one of many conditions, such as chronic bleeding of the endometrial layer of the uterus or abnormalities of the mucosal layer of the gallbladder. Existing methods for effecting ablation include circulation of heated fluid inside the organ (either directly or inside a balloon), laser treatment of the organ lining, and resistive heating using application of RF energy to the tissue to be ablated.
Ablation procedures are often carried out without direct endoscopic visualization. For example, ablation of the endometrial layer typically involves insertion of an elongate ablation device into the patient's uterus, without the use of a hysteroscope. As can be appreciated, the presence of a perforation in the uterus could result in inadvertent passage of the ablation device through the perforation and out of the uterus into the region adjacent the bowel. Although events of this nature are rare, the injury that could result from such occurrences make it highly desirable to provide a mechanism by which a physician can evaluate whether perforations are present in a body cavity before a treatment device such as an ablation device is used to deliver power.
In one approach for detecting perforation in a body cavity, a fluid (either liquid or gas) is delivered into the body cavity to slightly pressurize the cavity. A pressure sensing system monitors the pressure within the cavity for a predetermined test period. If cavity pressure is not substantially sustained during the test period, the physician is alerted to further assess the cavity for perforations before initiating treatment within the cavity. As can be appreciated, in order for such technique to work, the cervical os must be sealed during the operation period of the pressure sensing system. Otherwise, fluid may leak out from the cervical os, resulting in a pressure reading that is inaccurate.
Existing devices for sealing cervical os may not provide a hermetic seal at the external cervical os. This is particularly the case when the external os is angled such that it is not perpendicular or normal to the axis of the sealing device. Also, in some cases, the cervix may lack the firmness (patulous cervix) required for a good seal. To address such problems, doctors have sutured the os (opening) tissue to form a purse string seal (called a circlage), and have used a tenaculum to pinch the seal-os interface. However, such fixes may complicate the procedure and may not provide a desirable result.